VII 



MOLLUSCA— SYSTEMATIC REVIEW 



Lutrariidse, Myidse {Mya, Corhula). Fam. Glycymeridse (Glyq/mrris, Saxicava 

 [boring mussels]). Solenidse : shell with anterior and posterior cleft ; foot very 

 large {Solenocurtus, CuUeUus, Ensis, Solen). 



Sub-Order 6. Pholadacea. 

 Dimyarian with closed mantle and well-developed siphons. Foot varies, and is 



M^ jifo .flit jf 



Fig. 2Y.— Anatomy of Plioladidea, left aspect (after Egger). Lettering as before. In addition, 

 N]xi, Npp, anterior and posterior nerves of the mantle edge ; mo, anterior aperture of mantle ; Xis, 

 sac of the crystalline stylet ; Kr, branchial vein ; ol, anterior upper mantle lobe ; Rpp, posterior 

 retractor of the foot ; Ss, partition between the two siphons ; Ms, accessory adductor ; mh, intestinal 

 csecum ; x, pericardial section of the kidney, which opens into the pericardium by means of the 

 renal funnel at u. 



Rpp ^^ T M = 



M- 



Fio. 28.— Anatomy of Jouannetia Cumingli, left aspect (after Egger). Lettering as in 



last figure. 



sometimes rudimentary. Shell open, often having accessory pieces added to it. 

 Fam. Fholadidse: boring mussels {Pholas, Plwlcuiidea [Fig. 27], Jouannetia [Fig. 28], 



